Question

The sum of first 30 terms of an AP 2/5, 1, 8/5, 11/5.....is

Answer 1

Answer:

273

Step-by-step explanation:

if a=first term

common difference d=3/5

30th term=a+29d=89/5

sum=

30÷2×(first term+last term)

1. 15(2/5+89/5)

Answer 2

Answer:

sum of first n terms of an AP is sn = n{ 2a + ( n - 1)d }/2

where n is no of terms , a is first term, d is common difference

a = 2/5 , d = 1 - 2/5 = 3/5 , n = 30

= 30{ 2×2/5 + ( 30 - 1 ) 3/5 }/2

= 30{ 4/5 + 29×3/5}/2

= 30{ 4/5 + 87/5 } /2

= 30{ 91/5 }/2

= 546/2 = 273

sum of first 30 terms of the given series is 273